I used to sell water injection kits but have recently made it 'open source'. I think this kit is unique in that it includes an accumulator to prevent the pump for cycling on/off repeatedly, improving pump longevity. It also makes use of solenoids so that water is immediately available at the nozzle instead of waiting for the pump to make pressure. I ran this setup for many years on my 1991 MR2 turbo, and it is a very reliable and effective setup.

One thing that I would change is the nylon tubing - I would use braided lines instead. For the 1 series, I think it would be best to mount the tank/pump/accumulator setup outside the engine compartment protecting those components from heat/vibration. I would only mount the solenoid(s) inside the engine compartment, close to the point of injection. The pump used (Shurflo) has plenty of flow capability to handle multiple nozzles and sprayers for the intercooler if desired.
Hope you find this useful! I'm happy to answers questions about it!http://lovehorsepower.com/joomla/ind...=324&Itemid=93

It is for injecting water into a turbocharged engine, typically right before the throttle body. In addition, you can modify the setup to spray water onto the intercooler (like the STi and EVO) if you so desired.

The pump that is used here can support up to a 50% alcohol water mixture. The manufacture says that the internal seals can swell at higher alcohol levels. If you want to run 100% alcohol, a different pump is needed. The other components in the setup can handle alcohol.

On my personal MR2 turbo, the results with just water were impressive. I could run at least 4 more psi of boost (up from 16psi) with water injection. The limit being detonation. The advantage of running alcohol is your injecting additional high-octane fuel. Straight water will give you the best protection against detonation.